Final answer:
Direct delivery items are not delivered by Mattress Firm's regular delivery service but by a different carrier.
Step-by-step explanation:
The correct answer is A) They are delivered by a different carrier. When items are scheduled for direct delivery, they are not delivered by Mattress Firm's regular delivery service. Instead, they are typically delivered by the manufacturer or a third-party carrier. This is why these items do not appear on Mattress Firm's delivery tracker.